Infantry Drills

Section III: Obstacle Employment

Previous: H-121: Reduction Methods

H-124. Obstacles are used to reinforce the terrain. When combined with fires, they disrupt, fix, turn, or block an enemy force. Obstacles are used in all operations, but are most useful in defensive missions. Leaders must always consider what materials are needed and how long the obstacle will take to construct. (Refer to ATTP 3-90.4 for more information.)

H-125. A primary concern of the platoon and squad in the defense is to supplement their fortified positions with extensive protective obstacles, both antipersonnel and antivehicular (particularly AP). AP obstacles, both explosive and nonexplosive, include all those mentioned in Section I of this chapter (such as wire entanglements, AP mines, and field expedient devices), and are used to prevent enemy troops from entering a friendly position. Antipersonnel obstacles usually are integrated with fires and are close enough to the fortification for adequate surveillance by day or night, but beyond effective hand grenade range. Obstacles also are used within the position to compartmentalize the area in the event outer protective barriers are breached.

H-126. In the offense, the platoon/squad uses obstacles to:

  • Aid in flank security.
  • Limit enemy counterattack.
  • Isolate objectives.
  • Cut off enemy reinforcement or routes of withdrawal.

H-127. In the defense, the platoon/squad uses obstacles to—

  • Slow the enemy’s advance to give Infantry platoons and squads more time to mass fires on them.
  • Protect defending units.
  • Canalize the enemy into places where he can be engaged more easily.
  • Separate the enemy’s tanks from its Infantry.
  • Strengthen lightly defended areas.

Next: H-128: Mines

Go Back To: U.S. Army FM 3-21.8: The Infantry Rifle Platoon and Squad